SurfaceControl: Add setDropInputMode api

Introduces an API to drop input events on this SurfaceControl. This
policy will be inherited by its children. The caller must hold the
ACCESS_SURFACE_FLINGER permission.

Options include:
ALL: SurfaceControl and its children will not receive any
input regardless of whether it has a valid input channel.

These policies are used to enable features that allow for a less trusted
interaction model between apps. See the bug for more details.

Note: this backport does not include the OBSCURED option since its
not needed for the security fix.

Test: atest libgui_test InputDispatcherDropInputFeatureTest
Bug: 197296414

Merged-In: I443741d5ab51a45d37fb865f11c433c436d96c1e
Change-Id: I443741d5ab51a45d37fb865f11c433c436d96c1e

Author: Vishnu Nair

include/input/InputWindow.h

@@ -115,6 +115,7 @@ struct InputWindowInfo {
         INPUT_FEATURE_DISABLE_TOUCH_PAD_GESTURES = 0x00000001,
         INPUT_FEATURE_NO_INPUT_CHANNEL = 0x00000002,
         INPUT_FEATURE_DISABLE_USER_ACTIVITY = 0x00000004,
+        INPUT_FEATURE_DROP_INPUT = 0x00000008,
     };
 
     /* These values are filled in by the WM and passed through SurfaceFlinger

libs/gui/Android.bp

@@ -30,6 +30,14 @@ cc_library_headers {
     min_sdk_version: "29",
 }
 
+// AIDL files that should be exposed to java
+filegroup {
+    name: "guiconstants_aidl",
+    srcs: [
+        "android/gui/DropInputMode.aidl",
+    ],
+}
+
 cc_library_shared {
     name: "libgui",
     vendor_available: false,
@@ -41,6 +49,7 @@ cc_library_shared {
     defaults: ["libgui_bufferqueue-defaults"],
 
     srcs: [
+        ":guiconstants_aidl",
         ":framework_native_aidl",
         ":libgui_bufferqueue_sources",
 

libs/gui/LayerState.cpp

@@ -118,7 +118,7 @@ status_t layer_state_t::write(Parcel& output) const
     output.writeByte(frameRateCompatibility);
     output.writeUint32(fixedTransformHint);
     output.writeBool(isTrustedOverlay);
-
+    output.writeUint32(static_cast<uint32_t>(dropInputMode));
     return NO_ERROR;
 }
 
@@ -204,6 +204,9 @@ status_t layer_state_t::read(const Parcel& input)
     fixedTransformHint = static_cast<ui::Transform::RotationFlags>(input.readUint32());
     isTrustedOverlay = input.readBool();
 
+    uint32_t mode;
+    mode = input.readUint32();
+    dropInputMode = static_cast<gui::DropInputMode>(mode);
     return NO_ERROR;
 }
 
@@ -447,6 +450,10 @@ void layer_state_t::merge(const layer_state_t& other) {
         what |= eTrustedOverlayChanged;
         isTrustedOverlay = other.isTrustedOverlay;
     }
+    if (other.what & eDropInputModeChanged) {
+        what |= eDropInputModeChanged;
+        dropInputMode = other.dropInputMode;
+    }
     if ((other.what & what) != other.what) {
         ALOGE("Unmerged SurfaceComposer Transaction properties. LayerState::merge needs updating? "
               "other.what=0x%" PRIu64 " what=0x%" PRIu64,

libs/gui/SurfaceComposerClient.cpp

@@ -1497,6 +1497,21 @@ SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::setTrust
     return *this;
 }
 
+SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::setDropInputMode(
+        const sp<SurfaceControl>& sc, gui::DropInputMode mode) {
+    layer_state_t* s = getLayerState(sc);
+    if (!s) {
+        mStatus = BAD_INDEX;
+        return *this;
+    }
+
+    s->what |= layer_state_t::eDropInputModeChanged;
+    s->dropInputMode = mode;
+
+    registerSurfaceControlForCallback(sc);
+    return *this;
+}
+
 // ---------------------------------------------------------------------------
 
 DisplayState& SurfaceComposerClient::Transaction::getDisplayState(const sp<IBinder>& token) {

libs/gui/android/gui/DropInputMode.aidl

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) 2022, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.gui;
+
+
+/**
+  * Input event drop modes: Input event drop options for windows and its children.
+  *
+  * @hide
+  */
+@Backing(type="int")
+enum DropInputMode {
+    /**
+      * Default mode, input events are sent to the target as usual.
+      */
+    NONE,
+
+    /**
+      * Window and its children will not receive any input even if it has a valid input channel.
+      * Touches and keys will be dropped. If a window is focused, it will remain focused but will
+      * not receive any keys. If the window has a touchable region and is the target of an input
+      * event, the event will be dropped and will not go to the window behind. ref: b/197296414
+      */
+    ALL,
+}
+

libs/gui/include/gui/LayerState.h

@@ -25,6 +25,7 @@
 #include <gui/ITransactionCompletedListener.h>
 #include <math/mat4.h>
 
+#include <android/gui/DropInputMode.h>
 #ifndef NO_INPUT
 #include <input/InputWindow.h>
 #endif
@@ -106,6 +107,7 @@ struct layer_state_t {
         eProducerDisconnect = 0x100'00000000,
         eFixedTransformHintChanged = 0x200'00000000,
         eTrustedOverlayChanged = 0x400'00000000,
+        eDropInputModeChanged = 0x8000'00000000,
     };
 
     layer_state_t()
@@ -141,7 +143,8 @@ struct layer_state_t {
             frameRate(0.0f),
             frameRateCompatibility(ANATIVEWINDOW_FRAME_RATE_COMPATIBILITY_DEFAULT),
             fixedTransformHint(ui::Transform::ROT_INVALID),
-            isTrustedOverlay(false) {
+            isTrustedOverlay(false),
+            dropInputMode(gui::DropInputMode::NONE) {
         matrix.dsdx = matrix.dtdy = 1.0f;
         matrix.dsdy = matrix.dtdx = 0.0f;
         hdrMetadata.validTypes = 0;
@@ -243,6 +246,9 @@ struct layer_state_t {
     // An inherited state that indicates that this surface control and its children
     // should be trusted for input occlusion detection purposes
     bool isTrustedOverlay;
+
+    // Force inputflinger to drop all input events for the layer and its children.
+    gui::DropInputMode dropInputMode;
 };
 
 struct ComposerState {

libs/gui/include/gui/SurfaceComposerClient.h

@@ -531,7 +531,8 @@ class SurfaceComposerClient : public RefBase
 
         // Sets that this surface control and its children are trusted overlays for input
         Transaction& setTrustedOverlay(const sp<SurfaceControl>& sc, bool isTrustedOverlay);
-        
+
+        Transaction& setDropInputMode(const sp<SurfaceControl>& sc, gui::DropInputMode mode);
         status_t setDisplaySurface(const sp<IBinder>& token,
                 const sp<IGraphicBufferProducer>& bufferProducer);
 

services/surfaceflinger/Layer.cpp

@@ -119,6 +119,7 @@ Layer::Layer(const LayerCreationArgs& args)
     mCurrentState.treeHasFrameRateVote = false;
     mCurrentState.fixedTransformHint = ui::Transform::ROT_INVALID;
     mCurrentState.isTrustedOverlay = false;
+    mCurrentState.dropInputMode = gui::DropInputMode::NONE;
 
     if (args.flags & ISurfaceComposerClient::eNoColorFill) {
         // Set an invalid color so there is no color fill.
@@ -2645,6 +2646,16 @@ Layer::FrameRateCompatibility Layer::FrameRate::convertCompatibility(int8_t comp
     }
 }
 
+bool Layer::setDropInputMode(gui::DropInputMode mode) {
+    if (mCurrentState.dropInputMode == mode) {
+        return false;
+    }
+    mCurrentState.dropInputMode = mode;
+    mCurrentState.modified = true;
+    mCurrentState.inputInfoChanged = true;
+    setTransactionFlags(eTransactionNeeded);
+    return true;
+}
 // ---------------------------------------------------------------------------
 
 }; // namespace android

services/surfaceflinger/Layer.h

@@ -16,6 +16,7 @@
 
 #pragma once
 
+#include <android/gui/DropInputMode.h>
 #include <compositionengine/LayerFE.h>
 #include <gui/BufferQueue.h>
 #include <gui/ISurfaceComposerClient.h>
@@ -282,6 +283,8 @@ class Layer : public virtual RefBase, compositionengine::LayerFE {
 
         // Whether or not this layer is a trusted overlay for input
         bool isTrustedOverlay;
+
+        gui::DropInputMode dropInputMode;
     };
 
     explicit Layer(const LayerCreationArgs& args);
@@ -410,6 +413,8 @@ class Layer : public virtual RefBase, compositionengine::LayerFE {
     bool setShadowRadius(float shadowRadius);
     virtual bool setFrameRateSelectionPriority(int32_t priority);
     virtual bool setFixedTransformHint(ui::Transform::RotationFlags fixedTransformHint);
+    bool setDropInputMode(gui::DropInputMode);
+
     //  If the variable is not set on the layer, it traverses up the tree to inherit the frame
     //  rate priority from its parent.
     virtual int32_t getFrameRateSelectionPriority() const;

services/surfaceflinger/SurfaceFlinger.cpp

@@ -3867,6 +3867,15 @@ uint32_t SurfaceFlinger::setClientStateLocked(
             ALOGE("Attempt to set trusted overlay without permission ACCESS_SURFACE_FLINGER");
         }
     }
+    if (what & layer_state_t::eDropInputModeChanged) {
+        if (privileged) {
+            if (layer->setDropInputMode(s.dropInputMode)) {
+                flags |= eTraversalNeeded;
+            }
+        } else {
+            ALOGE("Attempt to update InputPolicyFlags without permission ACCESS_SURFACE_FLINGER");
+        }
+    }
     // This has to happen after we reparent children because when we reparent to null we remove
     // child layers from current state and remove its relative z. If the children are reparented in
     // the same transaction, then we have to make sure we reparent the children first so we do not